Yeah, it would help a lot if we knew your application.
Sounds like it might even be some kind of auto-sensing windshield wiper circuit for off-road
vehicle use.
It would be easier to point you in the right possible direction, if we knew your app.
I'm still trying to figure-out exactly what you're asking.
I'm thinking you're asking for voltage difference relating to common mode rejection ratio,
in the circuit you showed.
Theoretically, if both transistors are the same, you would have the same CMRR.
In actual practice, because components...
Seems like the top two question categories are:
Theory questions for school homework
Engineers/Techs with work-related problems they don't want to admit they need help with (for their jobs)
The funny (to me) third category, is Chinese businesses, trying to get sales leads.
It's enjoyable to me...
Some of those VFD (vacuum flourescent displays) operate at a high voltage, watch yourself. Google the part number on the display when you open the unit up, and find-out
what kind of display you've got. Then you can go from there.
If it IS a VFD, look for burned parts in the power supply to the...
They may make some kind of large matrix touch-switch board somewhere.
I'd be looking at sensitive touch (or push-button) small switches.
They have some that light when depressed, or you could get small switches, and tie them
to an LED/lens square, as the chess-board squares.
Somebody else might...
Ian seems to be on top of most of what I've seen (like davelectronic pointed out).
I got antsy when I saw the one guy wanting to know how to use a cell phone circuit
board to activate another circuit, he got shut down.
Or the kid claiming to be 10 years old who's dad didn't want him using a...
Are you sure that's not dirt/dust from elsewhere on your board?
That shouldn't have come out of an isopropyl container.
You didn't melt some kind of conformal coating on the board with the alcohol, did you?
I don't know, just doesn't make sense from simple isopropyl.
Odds are there are breaks in the heating elements in the pad itself.
You can disassemble the controller to have a look, but you're probably going to
have to replace the pad itself.
What exactly is the purpose of the stopwatch in this? Is it necessary?
There are plenty of cheap, readily available alarm clocks,
couldn't you just tie your hearing impared device into one of those?
Just wondering.
Hard to tell anymore. It depends on how the charge circuit is designed.
The battery MAY be damaged if the charge circuit doesn't back-off on charge current
when the battery is fully charged, OR,
The manufacturer knows the cheap Chinese batteries catch on fire when something
goes wrong, and...
Digi-Key, MCM Electronics, Jameco, Fry's Electronics, All Electronics Corp., Parts Express, Mouser, ....try to find local electronics supply stores where you're at.
Found it.
If anybody's interested:
http://www.dscc.dla.mil
microcircuit cross reference.
Dies owned by Rochester Electronics in Massacusetts, Vendor Part # 7800 303XA
Actual Device LM143H, High Voltage Op-Amp.
The site lists mil spec part number cross refs for mil spec electronic part numbers.
We're a little worried about you.
Your dad doesn't want you using a soldering iron because you're too young.
We recommend a solderless breadboard so you can try making some projects.
Now we find out one of your first project attempts is a Tesla Coil, and you're trying to
find some high...
You can try and IR sensor, but you've got loads of other options:
Proximity switches of all types, photo-detectors that would detect the light change as
somebody walked by the detector. Visible or IR lamp shining across the stairway to a
photo-detector. Hell, a tape-switch on one of the steps...
Maybe somebody else has an idea for you, I'm out of them.
If the mfgr date is not part of the lot code or serial number, the only people who'd know when
your detector was made, would be the mfgr.
If it was me, I'd try to return the detector for a replacement, citing defective unit.
As...